Astronaut training was not only physically tough, but it kept the astronauts away from their families for months at a time. If one of your parents were training for a dangerous mission, how would it change your relationship?

John Glenn sitting in a rotating chair for a "disorientation" test (1961) (NASA)

Glenn at the entrance to an altitude test chamber (1961) (NASA)

Astronaut Training

Do the astronauts have the stamina needed to reach space without passing out? Can they handle the risks, the unknown?

NASA needs to make sure. The country is counting on success. Astronaut training is difficult. In one test, the astronauts are spun around at high speed until the pressure on their bodies is 16 times that of their own weight. Glenn writes to a friend, "It took just about every bit of strength and technique to retain consciousness."

A NASA plane, dubbed the Vomit Comet, flies up and then down like a roller coaster. At the top of each arc, the men are weightless. Instead of getting sick, Glenn does flips and walks on the ceiling. He says, "I have finally found the element in which I belong."